Device and method for providing network slice interworking in wireless communication system

ABSTRACT

A pre-5th-Generation (5G) or 5G communication system for supporting higher data rates Beyond 4th-Generation (4G) communication system such as Long Term Evolution (LTE), in which a method performed by a user equipment (UE) includes transmitting, to a first base station (BS), a packet data network (PDN) connection request message, receiving, from the first BS, information on a first single-network slice selection assistance information (S-NSSAI) selected by a combination of a packet data network gateway control plane entity (PGW-C) and a session management function (SMF) from among the UE&#39;s at least one subscribed S-NSSAI, transmitting, to a second BS, a registration request message including a requested NSSAI in which the first S-NSSAI is included, and receiving, from the second BS, a registration accept message including an allowed NSSAI in which a second S-NSSAI mapped to the first S-NSSAI is included.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application of prior application Ser.No. 16/749,308, filed on Jan. 22, 2020, which is based on and claimedpriority under 35 U.S.C. § 119(a) of a Korean patent application number10-2019-0008381, filed on Jan. 22, 2019, of a Korean patent applicationnumber 10-2019-0017070, filed on Feb. 14, 2019, and of a Korean patentapplication number 10-2019-0037914, filed on Apr. 1, 2019, in the KoreanIntellectual Property Office, the disclosures of each of which areincorporated by reference herein in its entirety.

BACKGROUND 1. Field

The disclosure relates to a wireless communication system. Moreparticularly, the disclosure relates to a device and a method forproviding network slicing in a wireless communication system.

2. Description of Related Art

To meet the demand for wireless data traffic having increased sincedeployment of 4th generation (4G) communication systems, efforts havebeen made to develop an improved 5th generation (5G) or pre-5Gcommunication system. Therefore, the 5G or pre-5G communication systemis also called a ‘Beyond 4G Network’ or a ‘Post Long Term Evolution(LTE) System’.

The 5G communication system is considered to be implemented in higherfrequency (mmWave) bands, e.g., 28 GHz or 60 GHz bands, so as toaccomplish higher data rates. To decrease propagation loss of the radiowaves and increase the transmission distance, the beamforming, massivemultiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO),array antenna, an analog beam forming, large scale antenna techniquesare discussed in 5G communication systems.

In addition, in 5G communication systems, development for system networkimprovement is under way based on advanced small cells, cloud RadioAccess Networks (RANs), ultra-dense networks, device-to-device (D2D)communication, wireless backhaul, moving network, cooperativecommunication, Coordinated Multi-Points (CoMP), reception-endinterference cancellation and the like.

In the 5G system, Hybrid frequency shift keying (FSK) and quadratureamplitude modulation (FQAM) and sliding window superposition coding(SWSC) as an advanced coding modulation (ACM), and filter bank multicarrier (FBMC), non-orthogonal multiple access (NOMA), and sparse codemultiple access (SCMA) as an advanced access technology have beendeveloped.

In the 5G system, various communication schemes are discussed. Forexample, a grant-free communication scheme for transmitting data withoutgranting an uplink transmission is proposed. Furthermore, variousdiscussions for supporting the grant-free communication efficiently areunderway. The above information is presented as background informationonly to assist with an understanding of the disclosure. No determinationhas been made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the disclosure.

Based on the above discussion, the disclosure provides a method and adevice for interworking between an evolved packet system (EPS) networksystem and a 5G network system architecture for providing a networkslice function in a wireless communication system.

The above information is presented as background information only toassist with an understanding of the disclosure. No determination hasbeen made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the disclosure.

SUMMARY

Aspects of the disclosure are to address at least the above-mentionedproblems and/or disadvantages and to provide at least the advantagesdescribed below. Accordingly, an aspect of the disclosure is to providea device and method for providing network slicing in a wirelesscommunication system.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

In accordance with an aspect of the disclosure, a method for operating auser equipment (UE) in a wireless communication system is provided. Themethod comprises: transmitting, to a first base station (BS), a packetdata network (PDN) connection request message; receiving, from the firstBS, information on a first single-network slice selection assistanceinformation (S-NSSAI) selected by a combination of a packet data networkgateway control plane entity (PGW-C) and a session management function(SMF) from among the UE's at least one subscribed S-NSSAI; transmitting,to a second BS, a registration request message including a requestedNSSAI in which the first S-NSSAI is included; and receiving, from thesecond BS, a registration accept message including an allowed NSSAI inwhich a second S-NSSAI mapped to the first S-NSSAI is included.

In accordance with another aspect of the disclosure, a user equipment(UE) in a wireless communication system is provided. The UE comprises: atransceiver; and at least one processor operably coupled to thetransceiver, and configured to: transmit, to a first base station (BS),a packet data network (PDN) connection request message; receive, fromthe first BS, information on a first single-network slice selectionassistance information (S-NSSAI) selected by a combination of a packetdata network gateway control plane entity (PGW-C) and a sessionmanagement function (SMF) from among the UE's at least one subscribedS-NSSAI; transmit, to a second BS, a registration request messageincluding a requested NSSAI in which the first S-NSSAI is included; andreceive, from the second BS, a registration accept message including anallowed NSSAI in which a second S-NSSAI mapped to the first S-NSSAI isincluded.

A device and a method according to various embodiments of the disclosureprovide a method for interworking between an EPS network system and a 5Gnetwork system architecture for providing a network slice function, soas to effectively provide a service in a mobile communication system.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the disclosure will be more apparent from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 illustrates a 5G network slice interworking structure(non-roaming) according to an embodiment of the disclosure;

FIG. 2 illustrates a network slice interworking configuration(non-roaming) according to an embodiment of the disclosure;

FIG. 3 illustrates a network slice interworking configuration (localbreakout roaming) according to an embodiment of the disclosure;

FIG. 4 illustrates a network slice interworking configuration(home-routed roaming) according to an embodiment of the disclosure;

FIG. 5 illustrates session management function+packet data networkgateway-control (SMF+PGW-C) operation for supporting network sliceinterworking according to an embodiment of the disclosure;

FIG. 6 illustrates SMF+PGW-C operation for supporting network sliceinterworking according to an embodiment of the disclosure;

FIG. 7 illustrates a configuration of a base station in a wirelesscommunication system according to an embodiment of the disclosure;

FIG. 8 illustrates a configuration of a UE in a wireless communicationsystem according to an embodiment of the disclosure;

FIG. 9 illustrates a configuration of a core network device in awireless communication system according to an embodiment of thedisclosure; and

FIG. 10 illustrates a 5G network registration procedure of a UEaccording to an embodiment of the disclosure.

Throughout the drawings, like reference numerals will be understood torefer to like parts, components, and structures.

DETAILED DESCRIPTION

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiments of the disclosure as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the various embodiments describedherein can be made without departing from the scope and spirit of thedisclosure. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of thedisclosure. Accordingly, it should be apparent to those skilled in theart that the following description of various embodiments of thedisclosure is provided for illustration purpose only and not for thepurpose of limiting the disclosure as defined by the appended claims andtheir equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

The terms used in the disclosure are only used to describe specificembodiments, and may not be intended to limit ranges of otherembodiments. Unless defined otherwise, all terms used herein, includingtechnical and scientific terms, may have the same meaning as thosecommonly understood by a person skilled in the art to which thedisclosure pertains. Such terms as those defined in a generally useddictionary may be interpreted to have the meanings equal or similar tothe contextual meanings in the relevant field of art, and are not to beinterpreted to have ideal or excessively formal meanings unless clearlydefined in the disclosure. In some cases, even the term defined in thedisclosure should not be interpreted to exclude various embodiments ofthe disclosure.

Hereinafter, various embodiments of the disclosure will be describedbased on an approach of hardware. However, various embodiments of thedisclosure include a technology that uses both hardware and software,thus the various embodiments of the disclosure do not exclude asoftware-based approach.

The disclosure relates to a device and a method for providinginterworking of network slice in a wireless communication system.Specifically, the disclosure describes a technology for interworkingbetween an EPS network system and a 5G network system architecture forproviding a network slice function in a wireless communication system.

Terms used below are illustrated for convenience of description, theterms including a term indicating a signal, a term indicating a channel,a term indicating control information, a term indicating a networkentity, and a term indicating an element of a device. Accordingly, thedisclosure is not limited to the following terms and other terms havingthe same technical meaning may be used.

In addition, the disclosure describes various embodiments by using termsused in a part of communication standards (for example, a 3rd generationpartnership project (3GPP)), but the embodiments are only illustratedfor description. Various embodiments of the disclosure may be easilymodified and applied to other communication systems.

In 3GPP standards, a 5G network system architecture and procedure isstandardized. A mobile carrier can provide several services in a 5Gnetwork. In order to provide each service, a mobile carrier is requiredto meet different service demands for each service (for example, delaytime, communication range, data rate, bandwidth, reliability, etc.). Tothis end, a mobile carrier can constitute a network slice and allocate anetwork resource suitable for a specific service according to a networkslice or a network slice set. The network resource may indicate anetwork function (NF), a logical resource that the NF provides, or aradio resource allocation of a base station.

For example, a mobile carrier can constitute a network slice A toprovide a mobile broadband service, a network slice B to provide avehicle communication service, and a network slice C to provide an IoTservice. As described above, in a 5G network, a corresponding servicemay be provided on a network slice specialized for each servicecharacteristic. Single-network slice selection assistance information(S-NSSAI) defined by the 3GPP may be used as an identifier whichidentifies a network slice.

A mobile carrier can operate both a 5G network and an EPS (or calledLTE) network. A mobile communication UE can move to the EPS networkwhile accessing the 5G network and using a service. In addition, amobile communication UE can move to the 5G network while accessing theEPS network and using a service.

The disclosure defines a method for interworking between an EPS networksystem and a 5G network system architecture for providing a networkslice function. FIGS. 1, 2, and 3 illustrate an interworking structureof a 5G system (5GS) and an evolved packet system (EPS).

In addition, the disclosure defines a network operation and a UEoperation, in which a session connection is established in an EPS toenable a UE using a communication service to use a service withoutdisconnection even when the UE moves to a 5GS.

FIG. 1 illustrates an interworking structure of a 5GS and an EPS in acase of non-roaming according to an embodiment of the disclosure.

Referring to FIG. 1 , a 5GS may include a new radio (NR) base station150, an access and mobility management function (AMF) 145, a sessionmanagement function (SMF) 120, a user plane function (UPF) 125, a policycontrol function (PCF) 115, and an unified data management (UDM) 110. AnEPS may include an evolved universal terrestrial radio access (E-UTRA)base station 140, a mobility management entity (MME) 135, a servinggateway (SGW) 130, a packet data network gateway-user (PGW-U) 125, apacket data network gateway-control (PGW-C) 120, a policy and chargingrules function (PCRF) 115, and a home subscriber serve (HSS) 110. TheUDM 110 of the 5GS and the HSS 110 of the EPS may be constituted as asingle combo node. The SMF 120 of the 5GS and the PGW-C 120 of the EPSmay be constituted as a single combo node. A node of UDM+HSS 110 maystore UE subscription information. The UPF 125 of the 5GS and the PGW-U125 of the EPS may be constituted as a single combo node. A UE 155 mayaccess the MME 135 of the EPS via the E-UTRA base station 140 to use anEPS network service. In addition, the UE 155 may access the AMF 145 ofthe 5GS via the NR base station 150 to use a 5GS network service.

FIG. 2 illustrates an interworking structure of a 5GS and an EPS in acase of local breakout roaming according to an embodiment of thedisclosure. As illustrated in FIG. 1 , a UE 260 may access an MME 240 ofan EPS via an E-UTRA base station 245 to use an EPS network service.

Referring to FIG. 2 , in addition, the UE 260 may access an AMF 250 of a5GS via an NR base station 255 to use a 5GS network service. In theinterworking structure of a 5GS and an EPS in a case of local breakoutroaming, a node of SMF+PGW-C 225 may be located in a visited PLMN(VPLMN). N1, N2, N3, N8, N10, N11, N15, N26, S1-MME, S1-U, S6a, S11,S5-C and S5-U shown in FIG. 1 and FIG. 2 represent interfaces amongnetwork elements in the EPS and the 5GS.

FIG. 3 illustrates an interworking structure of a 5GS and an EPS in acase of home-routed roaming according to an embodiment of thedisclosure. As illustrated in FIG. 1 , a UE 370 may access an MME 335 ofan EPS via an E-UTRA base station 340 to use an EPS network service.

Referring to FIG. 3 , in addition, the UE 370 may access an AMF 360 of a5GS via an NR base station (NG-RAN) 365 to use a 5GS network service. Inthe interworking structure of a 5GS and an EPS in a case of home-routedroaming, a node of SMF+PGW-C 320 may be located in a home PLMN (HPLMN).N1, N2, N3, N8, N9, N10, N11, N15, N16, N24, N26, S1-MME, S1-U, S6a,S11, S8-C and S8-U shown in FIG. 3 represent interfaces among networkelements in the EPS and the 5GS.

FIG. 4 illustrates a procedure for establishing, by a UE 410 accordingto an embodiment of the disclosure, packet data network (PDN) connectionin an EPS.

Referring to FIG. 4 , the UE 410 may establish PDN connection byaccessing an MME 420 via an E-UTRA base station 415 to exchange asignaling message with a PGW-C 430 located in an EPS. When theestablishment of PDN connection is completed, the UE 410 may transmituplink data to a PGW-U 435 or receive downlink data from the PGW-U 435.

Procedure 1: the UE 410 may transmit a PDN connectivity request messageto the MME 420 for the establishment of PDN connection. The PDNconnectivity request message may be transmitted to the MME 420 via theE-UTRA base station 415.

Procedure 2: upon receiving the PDN connectivity request message inprocedure 1, the MME 420 may transmit a create session request messageto an S-GW 425.

Procedure 3: upon receiving the create session request message inprocedure 2, the S-GW 425 may transmit a create session request messageto the SMF+PGW-C 430.

Procedure 4: upon receiving the create session request message inprocedure 3, the SMF+PGW-C 430 may perform an internet protocolconnectivity access network (IP-CAN) session establishment/modificationprocedure along with a PCF+PCRF 440.

Procedure 5: upon receiving the create session request message inprocedure 3, the SMF+PGW-C 430 may transmit an Nudm_SDM_Get requestmessage to an UDM+HSS 445. The Nudm_SDM_Get request message may includea data type of requested subscription information, and information on akey accessible to the data type of the subscription information.According to an embodiment of the disclosure, “slice selectionsubscription data” may be included as a data type of requestedsubscription information, and UE's ID “SUPT” may be included as a keyaccessible to the data type of the subscription information.

Procedure 6: upon receiving the Nudm_SDM_Get request message inprocedure 5, the UDM+HSS 445 may, from a database (UDR), retrievenetwork slice subscription information of a UE corresponding to thereceived UE's ID SUPI, when the Nudm_SDM_Get request message includes aparameter “slice selection subscription data”. According to anembodiment of the disclosure, the network slice subscription informationmay be configured by at least one S-NSSAI, and be called subscribedS-NSSAIs. Upon retrieving subscribed S-NSSAIs of the UE corresponding tothe received SUPI, the UDM+HSS 445 may transmit an Nudm_SDM_Get responsemessage to the SMF+PGW-C 430. The Nudm_SDM_Get response message mayinclude “subscribed S-NSSAIs” information of the UE corresponding to theSUPI. The “subscribed S-NSSAIs” may include at least one defaultS-NSSAI. In order to describe the disclosure, the “subscribed S-NSSAIs”can be described by an example as follows.

Subscribed S-NSSAIs: {S-NSSAI 1, S-NSSAI 2, S-NSSAI 3(default)}

The UE 410 subscribes to three S-NSSAIs, and it may be assumed that,among the three S-NSSAIs, S-NSSAI 3 is a default S-NSSAI.

When PLMN ID included in the UE's ID SUPI matches PLMN ID in which theSMF+PGW-C 430 is located (that is, corresponding to the embodiments ofFIGS. 1 and 3 ), as illustrated in FIG. 5 , upon receiving theNudm_SDM_Get response message, the SMF+PGW-C 430 may perform anoperation of the SMF+PGW-C 430 of enabling the SMF+PGW-C 430 to selectan S-NSSAI.

FIG. 5 illustrates SMF+PGW-C operation for supporting network sliceinterworking according to an embodiment of the disclosure.

Referring to FIG. 5 , operations 510, 515 and 520 correspond toprocedures 3, 5 and 6 of FIG. 4 . Upon receiving the Nudm_SDM_Getresponse message (operation 520), the SMF+PGW-C 430 may identify(operation 525) whether an S-NSSAI, which the SMF+PGW-C 430 can provide,is included in the “subscribed S-NSSAIs” included in the Nudm_SDM_Getresponse message received in procedure 6.

When there is no S-NSSAI that the SMF+PGW-C 430 can provide (operation530) or when there is no S-NSSAI matching the “subscribed S-NSSAIs”received in procedure 6, among one or more S-NSSAIs that the SMF+PGW-C430 can provide (operation 530), the SMF+PGW-C 430 may select a defaultS-NSSAI from among the “subscribed S-NSSAIs” received in procedure 6(method 1), or may not select any S-NSSAI (method 2). In operation 550,the SMF-PGW-C may not include slice information in a create sessionresponse (method 2_1) or the SMF-PGW-C may reject the create sessionrequest (method 2_2). Alternatively, in operation 545, the createsession response message of procedure 9 may include slice information,which has been selected through the procedure.

When there is one S-NSSAI that the SMF+PGW-C 430 can provide and thecorresponding S-NSSAI is included in the “subscribed S-NSSAIs” receivedin procedure 6 (operation 535), or when there is one S-NSSAI matchingthe “subscribed S-NSSAIs” received in procedure 6, among two or moreS-NSSAIs that the SMF+PGW-C 430 can provide (operation 535), theSMF+PGW-C 430 may select one S-NSSAI which can be provided by theSMF+PGW-C 430 and is included in the “subscribed S-NSSAIs”. In operation545, the create session response message of procedure 9 may includeslice information, which has been selected through the procedure.

When there are two or more S-NSSAIs which the SMF+PGW-C 430 can provide,and among them, two or more S-NSSAIs are included in the “subscribedS-NSSAIs” (operation 540), the SMF+PGW-C 430 may select one S-NSSAI fromamong the two or more S-NSSAIs which are included in the “subscribedS-NSSAIs” and can be provided by the SMF+PGW-C 430, based on a mobilecarrier policy configured in the SMF+PGW-C 430. In operation 545, thecreate session response message of procedure 9 may include sliceinformation, which has been selected through the procedure.

When PLMN ID included in the UE's ID SUPI matches PLMN ID in which theSMF+PGW-C 430 is located (that is, corresponding to the embodiments ofFIGS. 1 and 3 ), procedures 7 and 8 may not be performed.

When PLMN ID included in the UE's ID SUPI does not match PLMN ID inwhich the SMF+PGW-C 430 is located (that is, corresponding to theembodiment of FIG. 2 ), procedures 7 and 8 may be performed.

Procedure 7: upon receiving the Nudm_SDM_Get response message inprocedure 6, the SMF+PGW-C 430 may transmit an Nnssf_NSSelection_Getrequest message to an NSSF 450. The Nnssf_NSSelection_Get requestmessage may include “PLMN ID” included in the UE's ID SUPI and the“subscribed S-NSSAIs” of the UE, received from the UDM+HSS 445 inprocedure 6. The “PLMN ID” included in the SUPI may indicate a UE'sHPLMN. The “subscribed S-NSSAIs” may indicate slice information used inthe UE's HPLMN.

Procedure 8: upon receiving the Nnssf_NSSelection_Get request message inprocedure 7, the NSSF 450 may derive “mapped S-NSSAIs” which are mappedwith the “subscribed S-NSSAIs” included in the request message to beused in a VPLMN. In order to describe the disclosure, the “subscribedS-NSSAIs” and the “mapped S-NSSAIs” can be described through an exampleas follows.

Subscribed S-NSSAIs: {S-NSSAI 1, S-NSSAI 2, S-NSSAI 3(default)}

Mapped S-NSSAIs: {(S-NSSAI 1, S-NSSAI a), (S-NSSAI 2, S-NSSAI b),(S-NSSAI 3, S-NSSAI c)}

S-NSSAIs included in the “subscribed S-NSSAIs” may be configured by aslice value (for example, S-NSSAI 1) used in the UE's HPLMN. S-NSSAIsincluded in the “mapped S-NSSAIs” may be configured by a pair (forexample, (S-NSSAI 1, S-NSSAI a)) of slice values (for example, S-NSSAIa) mapped with a slice value (for example, S-NSSAI 1) used in the UE'sHPLMN to be used in the VPLMN.

The NSSF 450 may transmit an Nnssf_NSSelection_Get response message tothe SMF+PGW-C 430. The Nnssf_NSSelection_Get response message mayinclude the “mapped S-NSSAIs”.

Upon receiving the Nnssf_NSSelection_Get response message, the SMF+PGW-C430 may perform an operation of the SMF+PGW-C 430 of enabling theSMF+PGW-C 430 to select an S-NSSAI as illustrated in FIG. 6 .

FIG. 6 illustrates SMF+PGW-C operation for supporting network sliceinterworking according to an embodiment of the disclosure.

Referring to FIG. 6 , operations 610, 615 and 620 correspond toprocedures 3, 6 and 8 of FIG. 4 . Upon receiving theNnssf_NSSelection_Get response message (operation 620), the SMF+PGW-C430 may identify (operation 625) whether an S-NSSAI, which can beprovided by the SMF+PGW-C 430 by using “mapped S-NSSAIs” informationincluded in the Nnssf_NSSelection_Get response message, is included inthe “subscribed S-NSSAIs” included in the Nudm_SDM_Get response messagereceived in procedure 6. For the operation above, the SMF+PGW-C 430 mayuse the received “mapped S-NSSAIs” information to interpret “subscribedS-NSSAIs” information.

For example, when a slice provided by the SMF+PGW-C 430 is S-NSSAI a,the SMF+PGW-C 430 may use the received “mapped S-NSSAIs” information toidentify that S-NSSAI 1 mapped with S-NSSAI a which is a slice providedby the SMF+PGW-C 430, is included in the “subscribed S-NSSAIs”.

Subscribed S-NSSAIs: {S-NSSAI 1, S-NSSAI 2, S-NSSAI 3(default)}

Mapped S-NSSAIs: {(S-NSSAI 1, S-NSSAI a), (S-NSSAI 2, S-NSSAI b),(S-NSSAI 3, S-NSSAI c)}

In addition, for example, when a slice provided by the SMF+PGW-C 430 isS-NSSAI d, the SMF+PGW-C 430 may use the received “mapped S-NSSAIs”information to identify that S-NSSAI d, which is a slice provided by theSMF+PGW-C 430, is not included in the “subscribed S-NSSAIs”.

Subscribed S-NSSAIs: {S-NSSAI 1, S-NSSAI 2, S-NSSAI 3(default)}

Mapped S-NSSAIs: {(S-NSSAI 1, S-NSSAI a), (S-NSSAI 2, S-NSSAI b),(S-NSSAI 3, S-NSSAI c)}

For example, when slices provided by the SMF+PGW-C 430 are S-NSSAI a andS-NSSAI d, the SMF+PGW-C 430 may use the received “mapped S-NSSAIs”information to identify that, among slices provided by the SMF+PGW-C430, S-NSSAI a is included in the “subscribed S-NSSAIs”, but S-NSSAI dis not included in the “subscribed S-NSSAIs”.

Subscribed S-NSSAIs: {S-NSSAI 1, S-NSSAI 2, S-NSSAI 3(default)}

Mapped S-NSSAIs: {(S-NSSAI 1, S-NSSAI a), (S-NSSAI 2, S-NSSAI b),(S-NSSAI 3, S-NSSAI c)}

For example, when slices provided by the SMF+PGW-C 430 are S-NSSAI a andS-NSSAI c, the SMF+PGW-C 430 may use the “mapped S-NSSAIs” informationreceived as follows, so as to identify that, both S-NSSAI a and S-NSSAIc, which are provided by the SMF+PGW-C 430, are included in the“subscribed S-NSSAIs”.

Subscribed S-NSSAIs: {S-NSSAI 1, S-NSSAI 2, S-NSSAI 3(default)}

Mapped S-NSSAIs: {(S-NSSAI 1, S-NSSAI a), (S-NSSAI 2, S-NSSAI b),(S-NSSAI 3, S-NSSAI c)}

When there is no S-NSSAI that the SMF+PGW-C 430 can provide (operation630), or when there is no S-NSSAI matching the “subscribed S-NSSAIs”received in procedure 6, among one or more S-NSSAIs (for example,S-NSSAI d) that the SMF+PGW-C 430 can provide (operation 630), theSMF+PGW-C 430 may select a default S-NSSAI from among the “subscribedS-NSSAIs” received in procedure 6 (method 1), or may not select anyS-NSSAI (method 2). In operation 650, the SMF-PGW-C may not includeslice information in a create session response (method 2_1) or theSMF-PGW-C may reject the create session request (method 2_2).Alternatively, in operation 645, the create session response message ofprocedure 9 may include slice information, which has been selectedthrough the procedure.

When there is one S-NSSAI (for example, S-NSSAI a) that the SMF+PGW-C430 can provide and the corresponding S-NSSAI is included in the“subscribed S-NSSAIs” received in procedure 6 (for example, S-NSSAI 1mapped with S-NSSAI a) (operation 635), or when there is one S-NSSAI(for example, S-NSSAI 1 mapped with S-NSSAI a, no S-NSSAI of HPLMN,mapped with S-NSSAI d) matching the “subscribed S-NSSAIs” received inprocedure 6, among two or more S-NSSAIs (for example, S-NSSAI a andS-NSSAI d) that the SMF+PGW-C 430 can provide (operation 635), theSMF+PGW-C 430 may select one S-NSSAI which can be provided by theSMF+PGW-C 430 and is included in the “subscribed S-NSSAIs”. That is, inoperation 645, the create session response message of procedure 9 mayinclude slice information, which has been selected through theprocedure.

When there are two or more S-NSSAIs that the SMF+PGW-C 430 can provide,and among them, two or more S-NSSAIs are included in the “subscribedS-NSSAIs” (operation 640), the SMF+PGW-C 430 may select one S-NSSAI fromamong the two or more S-NSSAIs which are included in the “subscribedS-NSSAIs” and can be provided by the SMF+PGW-C 430, based on a mobilecarrier policy configured in the SMF+PGW-C 430. That is, in operation645, the create session response message of procedure 9 may includeslice information, which has been selected through the procedure.

Procedure 9: upon receiving the Nudm_SDM_Get response message inprocedure 6 (i.e. the embodiments of FIGS. 1 and 3 ) or receiving theNnssf_NSSelection_Get response message in procedure 8 (i.e. theembodiment of FIG. 2 ), the SMF+PGW-C 430 may transmit a create sessionresponse message to the S-GW 425.

The create session response message may include slice information, whichhas been selected through the procedure of FIG. 5 or 6 , in the form ofprotocol configuration options (PCO) (operations 545, 645). The sliceinformation included in the create session response message may includevarious methods. The slice information included in the create sessionresponse message may be transmitted to the UE 410 through procedures 10,11, and 12.

In addition, the SMF+PGW-C 430 may store, in the UDM+HSS 445, S-NSSAI,which is slice information selected through the procedure of FIG. 5 or 6, and PDN connection information (for example, PDN connectivity ID etc.)supported by the S-NSSAI.

In a case of local breakout roaming (i.e. the embodiment of FIG. 2 ),according to an embodiment of the disclosure, an example of sliceinformation included in the create session response message will bedescribed. In order to describe an embodiment of the disclosure, it isassumed that the SMF+PGW-C 430 performs an operation of FIG. 6 to selectS-NSSAI 1 as follows.

Subscribed S-NSSAIs: {S-NSSAI 1, S-NSSAI 2, S-NSSAI 3(default)}

Mapped S-NSSAIs: {(S-NSSAI 1, S-NSSAI a), (S-NSSAI 2, S-NSSAI b),(S-NSSAI 3, S-NSSAI c)}

[LB embodiment 1]: the SMF+PGW-C 430 according to an embodiment of thedisclosure may allow S-NSSAI a, which is mapped to the selected S-NSSAI1 to be used in a VPLMN, to be included in the form of protocolconfiguration options (PCO), in the create session response message. ThePCO may include PLMN ID using S-NSSAI a, i.e. VPLMN ID.

Create Session Response msg: { . . . , PCO(S-NSSAI a)}

[LB embodiment 2]: the SMF+PGW-C 430 may allow S-NSSAI a, which ismapped to the selected S-NSSAI 1 to be used in a VPLMN, and mappinginformation corresponding to S-NSSAI a to be included in the form ofPCO, in the create session response message. The PCO may include PLMN IDusing S-NSSAI a, i.e. VPLMN ID.

Create Session Response msg: { . . . , PCO(S-NSSAI a, (S-NSSAI 1,S-NSSAI a))}

or

Create Session Response msg: { . . . , PCO((S-NSSAI 1, S-NSSAI a))}

[LB embodiment 3]: the SMF+PGW-C 430 may allow the selected S-NSSAI 1 tobe included in the form of PCO, in the create session response message.The PCO may include PLMN ID using S-NSSAI 1, i.e. HPLMN ID.

Create Session Response msg: { . . . , PCO(S-NSSAI 1)}

[LB embodiment 4]: the SMF+PGW-C 430 may allow the selected S-NSSAI 1and mapping information corresponding to S-NSSAI 1 to be included in theform of PCO, in the create session response message. The PCO may includePLMN ID using S-NSSAI 1, i.e. HPLMN ID, and PLMN ID using S-NSSAI a,i.e. VPLMN ID.

Create Session Response msg: { . . . , PCO(S-NSSAI 1, (S-NSSAI 1,S-NSSAI a))}

or

Create Session Response msg: { . . . , PCO((S-NSSAI 1, S-NSSAI a))}

[LB embodiment 5]: the SMF+PGW-C 430 may allow the selected sliceinformation not to be included in the create session response message.

Create Session Response msg: { . . . }

In a case of home-routed roaming (i.e. the embodiment of FIG. 3 ),according to an embodiment of the disclosure, an example of the sliceinformation included in the create session response message will bedescribed. In order to describe an embodiment of the disclosure, it isassumed that the SMF+PGW-C 430 performs an operation of FIG. 5 to selectS-NSSAI 1 as follows.

Subscribed S-NSSAIs: {S-NSSAI 1, S-NSSAI 2, S-NSSAI 3(default)}

[HR embodiment 1]: the SMF+PGW-C 430 according to an embodiment of thedisclosure may allow the selected S-NSSAI 1 to be included in the formof PCO, in the create session response message. The PCO may include PLMNID using S-NSSAI 1, i.e. HPLMN ID.

Create Session Response msg: { . . . , PCO(S-NSSAI 1)}

[HR embodiment 2]: the SMF+PGW-C 430 may allow the selected sliceinformation not to be included in the create session response message.

Create Session Response msg: { . . . }

Procedure 10: upon receiving the create session response message inprocedure 9, the S-GW 425 may transmit a create session response messageto the MME 420. The create session response message, which the S-GW 425transmits to the MME 420, may include the slice information included inthe create session response message received in procedure 9.

Procedure 11: upon receiving the create session response message inprocedure 10, the MME 420 may transmit a bearer setup request message ora “downlink NAS transport-with-PDN connectivity accept” message to theE-UTRA base station 415. The message, which the MME 420 transmits to theE-UTRA base station 415, may include the slice information included inthe create session response message received in procedure 10.

Procedure 12: upon receiving the bearer setup request message or the“downlink NAS transport-with-PDN connectivity accept” message inprocedure 11, the E-UTRA base station 415 may transmit an RRC connectionreconfiguration message or an RRC direct transfer message to the UE 410.The message, which the E-UTRA base station 415 transmits to the UE 410,may include the slice information included in the message received inprocedure 11.

Upon receiving the RRC connection reconfiguration message or the RRCdirect transfer message, the UE 410 may store S-NSSAI, i.e. the sliceinformation included in the message, and PLMN ID using the correspondingS-NSSAI. The slice information may be included in the form of PCO, inthe message.

Procedure 13: upon receiving the RRC connection reconfiguration messagein procedure 12, the UE 410 may transmit an RRC connectionreconfiguration complete message to the E-UTRA base station 415.

Procedure 14: upon receiving the RRC connection reconfiguration completemessage in procedure 13, the E-UTRA base station 415 may transmit abearer setup response message to the MME 420.

Procedure 15: upon receiving the RRC direct transfer message inprocedure 12, the UE 410 may transmit a direct transfer message to theE-UTRA base station 415.

Procedure 16: upon receiving the direct transfer message in procedure15, the E-UTRA base station 415 may transmit a PDN connectivity completemessage to the MME 420. Procedure 17: the MME 420 sends a modify bearerrequest to the S-GW 425. Procedure 18: the S-GW 425 forwards the modifybearer request to the SMF+PGW-C 430. Procedure 19: the SMF+PGW-C 430sends the modify bearer response to the S-GW 425. Procedure 20: the S-GW425 forwards the modify bearer response to the MME 420.

As illustrated in FIG. 4 , a UE according to an embodiment of thedisclosure may access an EPS network to establish PDN connection andtransmit or receive data. The UE may move to a 5GS network, and at thispoint, the UE may provide PDN connection-related information establishedin the EPS network, to the 5GS network.

FIG. 10 illustrates a process in which according to an embodiment of thedisclosure, the UE moves to the 5G network to perform a registrationprocedure. More specifically, a UE 260, 370, or 1010 moves to a 5GS totransmit a registration request message to an AMF 250, 360, or 1020.

Referring to FIG. 10 , the registration request message may include PDNconnection-related information established in an EPS network. The PDNconnection-related information may include requested NSSAI which isslice information requested by the UE, and other slice information (forexample, mapping information, indication, PLMN ID using an S-NSSAIincluded in the requested NSSAI, etc.). The requested NSSAI may beconfigured by at least one S-NSSAI. The registration request message maybe transmitted to the AMF 250, 360, or 1020 via an NG-RAN 255, 365, or1015. The PDN connection-related information included in theregistration request message may include various methods.

Hereinafter, in a case of local breakout roaming (i.e. the embodiment ofFIG. 2 ), an example of a method for, according to an embodiment of thedisclosure, providing PDN connection-related information established inan EPS, to a 5GS network will be described.

According to an embodiment, in a case of [LB embodiment 1] of procedure9 of FIG. 4 , a registration request message which a UE 260 or 1010according to an embodiment of the disclosure transmits to an AMF 250 or1020 via an NG-RAN 255 or 1015 may include S-NSSAI a received inprocedure 12 of FIG. 4 as requested NSSAI, and may include PLMN ID usingS-NSSAI a, i.e. VPLMN ID.

According to an embodiment, in a case of [LB embodiment 2] of procedure9 of FIG. 4 , a registration request message which a UE 260 or 1010according to an embodiment of the disclosure transmits to an AMF 250 or1020 via an NG-RAN 255 or 1015 may include S-NSSAI a received inprocedure 12 of FIG. 4 as requested NSSAI, and may include mappinginformation (S-NSSAI 1, S-NSSAI a) corresponding to S-NSSAI a, and PLMNID using S-NSSAI a, i.e. VPLMN ID.

When the UE's ID (for example, 5G-GUTI, GUTI, or SUPI) includesinformation allocated in an EPS, or when the received registrationrequest message includes VPLMN ID, the AMF 250 or 1020 according to [LBembodiment 1] and [LB embodiment 2] may identify that the requestedNSSAI included in the registration request received from the UE isconfigured by an S-NSSAI value used in a VPLMN.

According to an embodiment, in a case of [LB embodiment 3] of procedure9 of FIG. 4 , a registration request message which a UE 260 or 1010according to an embodiment of the disclosure transmits to an AMF 250 or1020 via an NG-RAN 255 or 1015 may include S-NSSAI 1 received inprocedure 12 of FIG. 4 as requested NSSAI, and may include PLMN ID usingS-NSSAI 1, i.e. HPLMN ID.

According to an embodiment, in a case of [LB embodiment 4] of procedure9 of FIG. 4 , a registration request message which a UE 260 or 1010according to an embodiment of the disclosure transmits to an AMF 250 or1020 via an NG-RAN 255 or 1015 may include S-NSSAI 1 received inprocedure 12 of FIG. 4 as requested NSSAI, and may include mappinginformation (S-NSSAI 1, S-NSSAI a) corresponding to S-NSSAI 1, and PLMNID using S-NSSAI 1, i.e. HPLMN ID.

When the UE's ID (for example, 5G-GUTI, GUTI, or SUPI) includesinformation allocated in an EPS, or when the received registrationrequest message includes HPLMN ID, the AMF 250 or 1020 according to [LBembodiment 3] and [LB embodiment 4] may identify that the requestedNSSAI included in the registration request received from the UE isconfigured by an S-NSSAI value used in an HPLMN.

According to an embodiment, in a case of [LB embodiment 5] of procedure9 of FIG. 4 , a registration request message, which a UE 260 or 1010according to an embodiment of the disclosure transmits to an AMF 250 or1020 via an NG-RAN 255 or 1015, may not include slice-relatedinformation. That is, the registration request message may not includerequested NSSAI.

When UE's ID (for example, 5G-GUTI, GUTI, or SUPI) includes informationallocated in an EPS, the AMF 250 or 1020 according to [LB embodiment 5]may identify that the UE is a UE which has moved from the EPS. The AMF250 or 1020 may obtain, from an UDM 210 of FIG. 2 or 1030 , PDNconnection information that the UE configures in the EPS, and S-NSSAIinformation supported by PDN connection. The AMF 250 or 1020 may allowthe S-NSSAI supported by PDN connection, which is obtained from the UDM210 or 1030, to be included in allowed NSSAI of a registration acceptmessage which is to be transmitted to the UE, and may then transmit theS-NSSAI.

Hereinafter, in a case of home-routed roaming (i.e. the embodiment ofFIG. 3 ), according to an embodiment of the disclosure, an example of amethod for providing, to a 5GS network, PDN connection-relatedinformation established in an EPS will be described.

According to an embodiment, in a case of [HR embodiment 1] of procedure9 of FIG. 4 , a registration request message which a UE 370 or 1010according to an embodiment of the disclosure transmits to an AMF 360 or1020 via an NG-RAN 365 or 1015 may include S-NSSAI 1 received inprocedure 12 of FIG. 4 as requested NSSAI. When the registration requestmessage includes S-NSSAI 1, the registration request message may includePDU session status of S-NSSAI 1.

According to an embodiment, in a case of [HR embodiment 1] of procedure9 of FIG. 4 , a registration request message which a UE 370 or 1010according to an embodiment of the disclosure transmits to an AMF 360 or1020 via an NG-RAN 365 or 1015 may include S-NSSAI 1 received inprocedure 12 of FIG. 4 as requested NSSAI, and may include indicationindicating that S-NSSAI 1 is a value used in an HPLMN. When theregistration request message includes S-NSSAI 1, the registrationrequest message may include PDU session status of S-NSSAI 1.

According to an embodiment, in a case of [HR embodiment 1] of procedure9 of FIG. 4 , a registration request message which a UE 370 or 1010according to an embodiment of the disclosure transmits to an AMF 360 or1020 via an NG-RAN 365 or 1015 may include S-NSSAI 1 received inprocedure 12 of FIG. 4 as requested NSSAI, and may include PLMN ID usingS-NSSAI 1, i.e. HPLMN ID. When the registration request message includesS-NSSAI 1, the registration request message may include PDU sessionstatus of S-NSSAI 1.

When UE's ID (for example, 5G-GUTI, GUTI, or SUPI) includes informationallocated in an EPS, when the received registration request messageincludes HPLMN ID, or when the received registration request messageincludes indication indicating an HPLMN value, the AMF 360 or 1020according to [HR embodiment 1] may identify that the requested NSSAIincluded in the registration request received from the UE is configuredby an S-NSSAI value used in an HPLMN.

In procedure 5 (operation 1055) of FIG. 10 , the AMF 360 or 1020 mayobtain “subscribed S-NSSAIs” information of a UE corresponding to theUE's ID from the UDM 310 of FIG. 3 or 1030 . The AMF 360 or 1020 maycompare requested NSSAI received from the UE 1010 with subscriptionslice information obtained from the UDM. If the S-NSSAI included in therequested NSSAI is included in the subscription slice information,procedure 6 (operation 1060) of FIG. 10 may be performed. Alternatively,procedure 5 (operation 1055) of FIG. 10 is omitted and procedure 6(operation 1060) may be directly performed. In addition, in procedure 6(operation 1060) of FIG. 10 , the AMF 360 or 1020 may transmit anNSSelection_Get request message to an NSSF 1025. The NSSelection_Getrequest message may include LIE subscription slice information, PLMN ID(i.e. HPLMN ID) included in LIE's ID (for example, SUPI), an HPLMNS-NSSAI value (according to an embodiment of the disclosure, S-NSSAI 1)which is received from the UE and by which the UE establishes a session,and requested NSSAI received from the UE.

The NSSF 1025 may determine a VPLMN S-NSSAI value which is mapped withthe HPLMN S-NSSAI value (for example, HPLMN S-NSSAI value included inrequested NSSAI) received from the AMF 360 or 1020 and is available in aVPLMN (i.e. serving PLMN which a UE currently accesses). The NSSF 1025may determine allowed NSSAI, based on the UE subscription sliceinformation, the VPLMN S-NSSAI value determined by the NSSF, and arequested NSSAI value. The allowed NSSAI may be configured by at leastone VPLMN S-NSSAI value available in a serving PLMN which the UEcurrently accesses. The NSSF 1025 may transmit an NSSelection_Getresponse message to the AMF 360 or 1020. The NSSelection_Get responsemessage may include the allowed NSSAI determined by the NSSF, andmapping of allowed NSSAI, corresponding to the allowed NSSAI. Uponreceiving the NSSelection_Get response message, the AMF 360 or 1020 maytransmit a registration accept message to the UE 1010 in procedure 7(operation 1065) and procedure 8 (operation 1070) of FIG. 10 . Theregistration accept message may include the allowed NSSAI and mapping ofallowed NSSAI, which are received from the NSSF. Upon receiving theregistration accept message, the UE 1010 may store the allowed NSSAI andthe mapping of allowed NSSAI, which are included in the registrationaccept message, and may use the same to manage(create/modify/delete) aPDU session in a current registration area and transmit or receive data.

According to an embodiment, in a case of [HR embodiment 1] of procedure9 of FIG. 4 , a registration request message which a UE 370 or 1010according to an embodiment of the disclosure transmits to an AMF 360 or1020 via an NG-RAN 365 or 1015 may not include requested NSSAI or mayconfigure an S-NSSAI value to be “unknown” in the requested NSSAI. Inaddition, the registration request message may include mappinginformation (S-NSSAI 1, unknown). That is, the UE may include S-NSSAI 1received in procedure 12 of FIG. 4 as an HPLMN S-NSSAI value of themapping information, and may configure the VPLMN S-NSSAI value to be“unknown” or may not include any value (empty). When the registrationrequest message includes S-NSSAI 1, the registration request message mayinclude PDU session status of S-NSSAI 1.

In procedure 5 (operation 1055) of FIG. 10 , the AMF 360 or 1020according to [HR embodiment 1] may obtain “subscribed S-NSSAIs”information of the UE corresponding to the UE's ID from the UDM 310 or1030. The AMF 360 or 1020 may compare the S-NSSAI value received fromthe UE and used in an HPLMN with the subscription slice informationobtained from the UDM. If the HPLMN S-NSSAI value received from the UEis included in the subscription slice information, procedure 6(operation 1060) of FIG. 10 may be performed. Alternatively, procedure 5(operation 1055) of FIG. 10 is omitted and procedure 6 (operation 1060)may be performed. The AMF 360 or 1020 may transmit an NSSelection_Getrequest message to the NSSF 1025 (operation 1055). The NSSelection_Getrequest message may include LIE subscription slice information, PLMN ID(i.e. HPLMN ID) included in LIE's ID (for example, SUPI), mappinginformation received from the UE, an HPLMN S-NSSAI value (according toan embodiment of the disclosure, S-NSSAI 1) which is received from theUE and by which the LIE establishes a session, and requested NSSAIreceived from the UE.

The NSSF 1025 may determine a VPLMN S-NSSAI value which is mapped withthe HPLMN S-NSSAI value (for example, HPLMN S-NSSAI value included inmapping information or HPLMN S-NSSAI value by which the UE establishes asession) received from the AMF 360 or 1020 and is available in a VPLMN(i.e. serving PLMN which the UE currently accesses). The NSSF 1025 maydetermine allowed NSSAI, based on UE subscription slice information, theHPLMN S-NSSAI value included in mapping information, the VPLMN S-NSSAIvalue determined by the NSSF, and a requested NSSAI value. The allowedNSSAI may be configured by at least one VPLMN S-NSSAI value available ina serving PLMN which the UE currently accesses. The NSSF 1025 maytransmit an NSSelection_Get response message to the AMF 360 or 1020. TheNSSelection_Get response message may include the allowed NSSAIdetermined by the NSSF and mapping of allowed NSSAI, corresponding tothe allowed NSSAI. Upon receiving the NSSelection_Get response message,the AMF 1020 may transmit a registration accept message to the UE 1010in procedure 7 (operation 1065) and procedure 8 (operation 1070) of FIG.10 . The registration accept message may include allowed NSSAI andmapping of allowed NSSAI, which are received from the NSSF. Uponreceiving the registration accept message, the UE 1010 may store theallowed NSSAI and mapping of allowed NSSAI which are included in theregistration accept message, and may use the same tomanage(create/modify/delete) a PDU session in a current registrationarea and transmit or receive data.

According to an embodiment, in a case of [HR embodiment 2] of procedure9 of FIG. 4 , a registration request message which a UE 370 or 1010according to an embodiment of the disclosure transmits to an AMF 360 or1020 via an NG-RAN 365 or 1015 may not include slice-relatedinformation. That is, the registration request message may not includerequested NSSAI.

When UE's ID (for example, 5G-GUTI, GUTI, or SUPI) includes informationallocated in an EPS, the AMF 360 or 1020 according to [HR embodiment 2]may identify that the UE is a UE which has moved from the EPS. The AMF360 or 1020 may obtain, from the UDM 1030, PDN connection informationthat the UE configures in the EPS, and S-NSSAI information supported byPDN connection. The AMF 360 or 1020 may allow an S-NSSAI supported byPDN connection, which is obtained from the UDM 310 or 1030, to beincluded in allowed NSSAI of the registration accept message, and maytransmit the message to the UE 370 or 1010.

According to an embodiment of the disclosure, an operation ofdetermining allowed NSSAI and mapping of allowed NSSAI may be performedby the AMF 1020, not by the NSSF 1025. That is, procedure 6 (operation1060) of FIG. 10 may be processed by an internal operation of the AMF.

A UE according to an embodiment of the disclosure may store sliceinformation which is included in the form of PCO, in the messagereceived in procedure 12 of FIG. 4 . The slice information in the formof PCO, received by the UE, may indicate an “S-NSSAI” value connected toPDN connection, “PLMN ID” using the corresponding S-NSSAI, and “mappedslice” information. The UE may compare the received slice informationwith slice policy information (for example, UE route selection policy(URSP), network slice selection policy (NSSP), UE local policy, etc.)previously stored in the UE, and may determine whether the sliceinformation matches the slice policy information. Table 1 represents anexample of the slice policy information stored in the UE.

TABLE 1 Application identifier Slice identifier (S-NSSAI) Application id#1 S-NSSAI 1 Application id #2 S-NSSAI 2 Application id #3 S-NSSAI 1,S-NSSAI 2 Matching all S-NSSAI 3

The slice policy information stored in the UE includes applicationsinstalled in the UE and slice information used to use each of theapplications. For example, in a case of application id #1 of the UE,S-NSSAI 1 is used to provide a service. A UE which intends to useapplication id #1 may perform a registration procedure by accessing a 5Gnetwork. In the registration procedure, the UE may transmit aregistration request message to a network, thus the registration requestmessage may include slice information (S-NSSAI) that the UE intends touse, in the form of requested NSSAI. In the registration procedure, theUE may receive, from the network, allowed NSSAI which is sliceinformation that the UE can use by accessing the network. The UE may usethe allowed NSSAI and the slice policy information to, when transmittinga PDU session establishment request message for application id #1, allowS-NSSAI 1 to be included in the PDU session establishment requestmessage.

When the PCO received by the UE includes an “S-NSSAI” value (forexample, S-NSSAI 1) and “PLMN ID” using the corresponding S-NSSAI, i.e.HPLMN ID, the UE may use the slice policy information stored in the UEto identify slice information mapped with an application that the UEuses by accessing the EPS and generating PDN connection.

When an application that the UE currently uses is application id #1, aslice having been identified based on the slice policy informationstored in the UE may be S-NSSAI 1. In this case, it may be determinedthat the slice (S-NSSAI 1) having been identified based on the slicepolicy information stored in the UE matches slice information(S-NSSAI 1) received using the PCO. When in procedure 1 (operation 1035)of FIG. 10 , requested NSSAI and mapping of requested NSSAI aregenerated, the UE may allow S-NSSAI 1 to be included in the requestedNSSAI or the mapping of requested NSSAI.

Alternatively, when an application that the UE currently uses isapplication id #2, a slice having been identified based on the slicepolicy information stored in the UE may be S-NSSAI 2. In this case, itmay be determined that the slice (S-NSSAI 2) having been identifiedbased on the slice policy information stored in the UE does not matchslice information (S-NSSAI 1) received using the PCO. When in procedure1 (operation 1035) of FIG. 10 , requested NSSAI and mapping of requestedNSSAI are generated, the UE may allow S-NSSAI 1 and S-NSSAI 2 to beincluded in the requested NSSAI or the mapping of requested NSSAI.

When the PCO received by the UE includes an “S-NSSAI” value (forexample, S-NSSAI a), “PLMN ID” using the corresponding S-NSSAI, i.e.VPLMN ID, and “mapped slice information” (for example, {S-NSSAI 1,S-NSSAI a}), the UE may use the slice policy information stored in theUE to identify slice information mapped with an application that the UEuses by accessing the EPS and generating PDN connection.

When an application that the UE currently uses is application id #1, aslice having been identified based on the slice policy informationstored in the UE may be S-NSSAI 1. In this case, it may be determinedthat the slice (S-NSSAI 1) having been identified based on the slicepolicy information stored in the UE matches slice information ({S-NSSAI1, S-NSSAI a}) received using the PCO. When in procedure 1 (operation1035) of FIG. 10 , requested NSSAI and mapping of requested NSSAI aregenerated, the UE may allow S-NSSAI a to be included in the requestedNSSAI, and may allow {S-NSSAI 1, S-NSSAI a} to be included in themapping of requested NSSAI.

Alternatively, when an application that the UE currently uses isapplication id #2, a slice having been identified based on the slicepolicy information stored in the UE may be S-NSSAI 2. In this case, itmay be determined that the slice (S-NSSAI 2) having been identifiedbased on the slice policy information stored in the UE does not matchslice information ({S-NSSAI 1, S-NSSAI a}) received using the PCO. Whenin procedure 1 (operation 1035) of FIG. 10 , requested NSSAI and mappingof requested NSSAI are generated, the UE may allow S-NSSAI a and unknownindication to be included in the requested NSSAI, and may allow {S-NSSAI1, S-NSSAI a} and {S-NSSAI 2, unknown(or empty)} to be included in themapping of requested NSSAI.

Referring to FIG. 10 , in procedure 2 (operation 1040), the UE 1010 maytransmit a registration request message to the base station 1015 inorder to register in a communication system. In procedure 3 (operation1045), the base station 1015 performs requested NSSAI identification andAMF selection based on slice information. In procedure 4 (operation1050), the base station 1015 may transmit the registration requestmessage to the AMF 1020 to access.

The registration request message transmitted in procedures 2 and 4(operations 1040, 1050) may include requested NSSAI which the UE 1010intends to use after registering in a communication system. In procedure1 (operation 1035), the requested NSSAI may be determined by the UE1010, based on configured NSSAI. The requested NSSAI and the configuredNSSAI may be configured by at least one S-NSSAI.

In procedure 5 (operation 1055), upon receiving the registration requestmessage 1050, the AMF 1020 may obtain UE subscription information fromthe UDM 1030. The UE subscription information may include subscribedS-NSSAIs of the UE 1010.

In procedure 6 (operation 1060), the AMF 1020 may determine therequested NSSAI received from the UE 1010 in procedure 4 (operation1050), the subscribed S-NSSAIs received from the UDM 1030 in procedure 5(operation 1055), and allowed NSSAI which, based on the sliceinformation available at the current position of the UE 1010, the UE1010 can use after registering in a communication system.

In procedure 6 (operation 1060), the AMF 1020 may request the NSSF 1025to determine allowed NSSAI. To this end, the AMF 1020 may provide, tothe NSSF 1025, the requested NSSAI received from the UE 1010 inprocedure 4 (operation 1050), the subscribed S-NSSAIs received from theUDM 1030 in procedure 5 (operation 1055), and current positioninformation of the UE 1010. The NSSF 1025 may determine allowed NSSAI,which the UE 1010 can use after registering in a communication system,based on the information received from the AMF 1020 and the sliceinformation available at the current position of the UE 1010. The NSSF1025 may transmit the allowed NSSAI to the AMF 1020.

At this point, if there is no slice that a UE can use after registeringin a communication system, the AMF 1020 and the NSSF 1025 may generaterejected S-NSSAIs with respect to the slice included in the requestedNSSAI received from the UE 1010 in procedure 4 (operation 1050), and mayconstitute allowed NSSAI by using various methods as follows.

According to one or more embodiments, the AMF 1020 or the NSSF 1025 mayidentify subscribed S-NSSAIs of the UE 1010, and if a default S-NSSAI isincluded in the subscribed S-NSSAIs, the AMF 1020 or the NSSF 1025 mayallow the default S-NSSAI to be included in the allowed NSSAI. Accordingto an embodiment, if a default S-NSSAI is not included in the subscribedS-NSSAIs, the AMF 1020 or the NSSF 1025 may configure the subscribedS-NSSAIs to be “empty”, or may determine the subscribed S-NSSAIs not tobe transmitted to the UE 1010.

According to one or more embodiments, the AMF 1020 or the NSSF 1025 mayconfigure the subscribed S-NSSAIs to be “empty”.

According to one or more embodiments, the AMF 1020 or the NSSF 1025 maydetermine the subscribed S-NSSAIs not to be transmitted to the UE 1010.

Upon determining (or obtaining, from the NSSF 1025,) the allowed NSSAIand rejected S-NSSAIs in procedure 6 (operation 1060), the AMF 1020 mayallow at least one of the allowed NSSAI and rejected S-NSSAIs to beincluded in the registration accept message transmitted to the UE 1010in procedure 7 (operation 1065). The registration accept message ofprocedure 7 (operation 1065) may be transmitted to the UE 1010 via thebase station 1015 in procedure 8 (operation 1070).

Upon receiving the registration accept message in procedure 8 (operation1070), the UE 1010 may identify the allowed NSSAI and/or rejectedS-NSSAIs included in the registration accept message and may perform anoperation as follows.

According to one or more embodiments, if the registration accept messagereceived in procedure 8 (operation 1070) includes only the rejectedS-NSSAIs and does not include the allowed NSSAI, the UE 1010 mayidentify that all the requested slices, which the UE requests from anetwork through procedures 1, 2, and 4 (operations 1035, 1040, 1050),are rejected. Therefore, the UE 1010 may not send a PDU session requestuntil receiving the allowed NSSAI from the network. Alternatively, whenthe UE sends a PDU session request until receiving the allowed NSSAIfrom the network, the UE 1010 may not include the S-NSSAI. Uponreceiving the PDU session request message which does not include theS-NSSAI, the network (for example, SMF or AMF) may select a defaultS-NSSAI and generate a PDU session, based on subscription information ofthe UE 1010.

According to one or more embodiments, when the registration acceptmessage received in procedure 8 (operation 1070) includes the rejectedS-NSSAIs and the allowed NSSAI is configured to be “empty”, the UE 1010may identify that all the requested slices, which the UE requests from anetwork through procedures 1, 2, and 4 (operations 1035, 1040, 1050),are rejected. Therefore, the UE 1010 may not send a PDU session requestuntil receiving the allowed NSSAI from the network. Alternatively, whenthe UE sends a PDU session request until receiving the allowed NSSAIfrom the network, the UE 1010 may not include the S-NSSAI. Uponreceiving the PDU session request message which does not include theS-NSSAI, the network (for example, SMF or AMF) may select a defaultS-NSSAI and generate a PDU session, based on subscription information ofthe UE 1010.

According to one or more embodiments, if the rejected S-NSSAIs of theregistration accept message received in procedure 8 (operation 1070)includes all the requested slices, which the UE 1010 requests from anetwork through procedures 1, 2, and 4 (operations 1035, 1040, 1050)(that is, all the requested slices of the UE are rejected) and theallowed NSSAI includes the S-NSSAIs, the UE 1010 may identify that allthe requested slices, which the UE requests from a network throughprocedures 1, 2, and 4 (operations 1035, 1040, 1050), are rejected.Further, the UE 1010 may use the allowed NSSAIs, which the UE 1010 hasreceived in procedure 8 (operation 1070) until receiving new allowedNSSAI from the network, in order to send a PDU session request.According to one embodiment, when the UE sends a PDU session request,the UE 1010 may allow one S-NSSAI of the allowed NSSAIs received inprocedure 8 (operation 1070), to be included in the PDU session requestmessage.

FIG. 7 illustrates a configuration of a base station in a wirelesscommunication system, according to an embodiment of the disclosure. Theconfiguration illustrated in FIG. 7 may be understood as a configurationof a base station 140, 245, or 340 of an EPS or a base station 150, 255,or 365 of a 5GS. The term “˜unit” or “˜er” used hereinafter may refer tothe unit for processing at least one function or operation and may beimplemented in hardware, software, or a combination of hardware andsoftware.

Referring to FIG. 7 , a base station includes a wireless communicationunit 710, a backhaul communication unit 720, a storage unit 730, and acontrol unit 740.

The wireless communication unit 710 executes functions for transmittingor receiving signals through a wireless channel. For example, thewireless communication unit 710 performs a function of conversionbetween a baseband signal and a bit stream according to a physical layerstandard of a system. For example, when data is transmitted, thewireless communication unit 710 encodes and modulates a transmission bitstream so as to generate complex symbols. In addition, when data isreceived, the wireless communication unit 710 restores a reception bitstream by demodulating and decoding a baseband signal.

The wireless communication unit 710 up-converts a baseband signal into aradio-frequency (RF) band signal and transmits the same through anantenna, and down-converts an RF band signal received through an antennainto a baseband signal. To this end, the wireless communication unit 710may include a transmission filter, a reception filter, an amplifier, amixer, an oscillator, a digital-to-analog convertor (DAC), ananalog-to-digital convertor (ADC), and the like. In addition, thewireless communication unit 710 may include multipletransmission/reception paths. The wireless communication unit 710 mayinclude at least one antenna array configured by multiple antennaelements.

In an aspect of hardware, the wireless communication unit 710 mayinclude a digital unit and an analog unit, and the analog unit mayinclude multiple sub-units according to operation power, operationfrequency, and the like. The digital unit may be implemented as at leastone processor (for example, digital signal processor (DSP)).

The wireless communication unit 710 may transmit or receive a signal asdescribed above. Therefore, the entire or a part of the wirelesscommunication unit 710 may be called a “transmitter”, “receiver”, or“transceiver”. Hereinafter, the transmission and reception performedthrough a wireless channel may be understood to mean that theabove-described processing is performed by the wireless communicationunit 710.

The backhaul communication unit 720 provides an interface for performingcommunication with other nodes in a 5GS network or EPS network. That is,the backhaul communication unit 720 converts a bit stream transmittedfrom a base station to another node, for example, another access node,another base station, an upper node, or a core network, into a physicalsignal, and converts a physical signal received from another node into abit stream.

The storage unit 730 may store data, such as a basic program foroperating a base station, an application program, and configurationinformation. The storage unit 730 may be configured as a volatilememory, a non-volatile memory, or a combination of a volatile memory anda non-volatile memory. The storage unit 730 provides stored dataaccording to a request of the control unit 740.

The control unit 740 may control the overall operation of a basestation. For example, the control unit 740 transmits or receives asignal via the wireless communication unit 710 or the backhaulcommunication unit 720. In addition, the control unit 740 records datain the storage unit 730 and reads the data. The control unit 740 mayperform functions of a protocol stack, which are required bycommunication standards. According to other embodiments, a protocolstack may be included in the wireless communication unit 710. To thisend, the control unit 740 may include at least one processor. Accordingto various embodiments, the control unit 740 may include functions fornetwork slicing interworking. The functions for network slicinginterworking are instruction sets or codes stored in the storage unit730, and may be instructions/codes residing at least temporarily in thecontrol unit 740, a storage space in which instructions/codes arestored, or a part of a circuitry constituting the control unit 740.

According to various embodiments, the control unit 740 may receive adownlink NAS transport-with-PDN connectivity accept message or a bearersetup request message, which includes slice information, for networkslicing interworking, and may control an RRC direct transfer message oran RRC connection reconfiguration message which may include sliceinformation to be transmitted to a UE. For example, the control unit 740may control the base station to perform operations according to variousembodiments described above.

FIG. 8 illustrates a configuration of a UE in a wireless communicationsystem, according to an embodiment of the disclosure. The configurationillustrated in FIG. 8 may be understood as a configuration of a UE 155,260, or 370. The term “˜unit” or “˜er” used hereinafter may refer to theunit for processing at least one function or operation and may beimplemented in hardware, software, or a combination of hardware andsoftware.

Referring to FIG. 8 , a UE includes a communication unit 810, a storageunit 820, and a control unit 830.

The communication unit 810 executes functions for transmitting orreceiving a signal through a wireless channel. For example, thecommunication unit 810 performs a function of conversion between abaseband signal and a bit stream according to a physical layer standardof a system. For example, when data is transmitted, the communicationunit 810 encodes and modulates a transmission bit stream so as togenerate complex symbols. In addition, when data is received, thecommunication unit 810 restores a reception bit stream by demodulatingand decoding a baseband signal. The communication unit 810 up-converts abaseband signal into a RF band signal and transmits the same through anantenna, and down-converts an RF band signal received through an antennainto a baseband signal. For example, the communication unit 810 mayinclude a transmission filter, a reception filter, an amplifier, amixer, an oscillator, a DAC, an ADC, and the like.

In addition, the communication unit 810 may include multipletransmission/reception paths. The communication unit 810 may include atleast one antenna array configured by multiple antenna elements. In anaspect of hardware, the communication unit 810 may include a digitalcircuit and an analog circuit (for example, radio frequency integratedcircuit (RFIC)). The digital circuit and the analog circuit may beimplemented as a single package. In addition, the communication unit 810may include multiple RF chains. The communication unit 810 may performbeam-forming

The communication unit 810 may include different communication modulesto process signals within different frequency bands. In addition, thecommunication unit 810 may include a plurality of communication modulesfor supporting a plurality of different radio access technologies. Forexample, different radio access technologies may include Bluetooth lowenergy (BLE), wireless fidelity (Wi-Fi), WiFi gigabyte (WiGig), acellular network (for example, long term evolution (LTE)), a 5G network,and the like. In addition, different frequency bands may include a superhigh frequency (SHF) (for example, 2.5 GHz and 5 GHz) band and amillimeter (mm) wave (for example, 60 GHz) band.

The communication unit 810 may transmit or receive a signal as describedabove. Therefore, the entire or a part of the communication unit 810 maybe called a “transmitter”, “receiver”, or “transceiver”. Hereinafter,the transmission and reception performed through a wireless channel maybe understood to mean that the above-described processing is performedby the communication unit 810.

The storage unit 820 may store data, such as a basic program foroperating a UE, an application program, configuration information, andthe like. The storage unit 820 may be configured as a volatile memory, anon-volatile memory, or a combination of a volatile memory and anon-volatile memory. The storage unit 820 provides stored data accordingto a request of the control unit 830.

The control unit 830 may control the overall operation of a UE. Forexample, the control unit 830 transmits or receives a signal via thecommunication unit 810. In addition, the control unit 830 records datain the storage unit 820 and reads the data. The control unit 830 mayperform functions of a protocol stack, which are required bycommunication standards. To this end, the control unit 830 may includeat least one processor or micro-processor, or may be a part of aprocessor. The part of the communication unit 810 and the control unit830 may be called a communication processor (CP). According to variousembodiments, the control unit 830 may include a function for supportingnetwork slicing. The function for supporting network slicing is aninstruction set or code stored in the storage unit 820, and may be aninstruction/code residing at least temporarily in the control unit 830,a storage space in which instructions/codes are stored, or a part of acircuitry constituting the control unit 830.

According to various embodiments, the control unit 830 may control a UEto access the MME 420 via the E-UTRA base station 415 to exchange asignaling message with the PGW-C 430 located in an EPS and establish PDNconnection, and when the establishment of PDN connection is completed,may control the UE 410 to transmit uplink data to the PGW-U 435 orreceive downlink data from the PGW-U 435. Particularly, the control unit830 may receive an RRC connection reconfiguration message or an RRCdirect transfer message from the base station, and may store S-NSSAI,i.e. slice information included in the message, and PLMN ID using thecorresponding S-NSSAI. For example, the control unit 830 may control theUE to perform operations according to various embodiments describedabove.

FIG. 9 illustrates a configuration of a core network entity in awireless communication system, according to an embodiment of thedisclosure. The configuration illustrated in FIG. 9 may be understood asa configuration of an apparatus having at least one function of theHSS+UDM 110, 210, or 310, PCF+PCRF 115, 215, 220, or 315, SMF+PGW-C 120,225, or 320, UPF+PGW-U 125, 230, or 325, SGW 130, 235, or 330, MME 135,240, or 335, AMF 145, 250, or 360, UPF 355, v-SMF 350, and vPCF 345 ofFIGS. 1 to 3 . The term “˜unit” or “˜er” used hereinafter may refer tothe unit for processing at least one function or operation and may beimplemented in hardware, software, or a combination of hardware andsoftware.

Referring to FIG. 9 , a core network entity includes a communicationunit 910, a storage unit 920, and a control unit 930.

The communication unit 910 provides an interface for performingcommunication with other devices in a network. That is, thecommunication unit 910 converts a bit stream transmitted from a corenetwork entity to a different device, into a physical signal, andconverts a physical signal received from a different device, into a bitstream. That is, the communication unit 910 may transmit or receive asignal. Therefore, the communication unit 910 may be called a “modem”,“transmitter”, “receiver”, or “transceiver”. The communication unit 910may allow the core network entity to communicate with other devices or asystem via backhaul connection (for example, wire backhaul or wirelessbackhaul) or via a network.

The storage unit 920 stores data such as a basic program for theoperation of the core network entity, an application program, andconfiguration information. The storage unit 920 may be configured as avolatile memory, a non-volatile memory, or a combination of a volatilememory and a non-volatile memory. The storage unit 920 provides storeddata according to a request of the control unit 930.

The control unit 930 controls the entire operations of the core networkentity. For example, the control unit 930 transmits or receives a signalvia the communication unit 910. In addition, the control unit 930records data in the storage unit 920 and reads the data. To this end,the control unit 930 may include at least one processor. According tovarious embodiments, the control unit 930 may include a function forsupporting network slicing. The function for supporting network slicingmay be implemented by an instruction set or code stored in the storageunit 920, and may be an instruction/code residing at least temporarilyin the control unit 930, a storage space in which an instruction/code isstored, or a part of a circuitry constituting the control unit 930.

According to various embodiments, the control unit 930 may: receive acreate session request message; transmit an Nudm_SDM_Get requestmessage; receive an Nudm_SDM_Get response message; compare the receivedsubscribed S-NNSAIs with S-NSSAI information that the SMF-PGW-C providesby itself to select an S-NSSAI to be used; and control a function ofenabling the S-SNSSAI to be included in a create session responsemessage and transmitting the same to the UE, and the control unit 930may perform control such that the core network entity performsoperations according to various embodiments described above.

Methods according to claims of the disclosure or embodiments disclosedin the specification may be implemented in the form of hardware,software, or a combination of hardware and software.

When the methods are implemented by software, a computer-readablestorage medium for storing one or more programs (software modules) maybe provided. The one or more programs stored in the computer-readablestorage medium may be configured for execution by one or more processorswithin the electronic device. The at least one program includesinstructions that cause an electronic device to perform the methodsaccording to embodiments disclosed in the claims or the specification ofthe disclosure.

The programs (software module, software) may be stored in non-volatilememories including a random access memory and a flash memory, a readonly memory (ROM), an electrically erasable programmable read onlymemory (EEPROM), a magnetic disc storage device, a compact disc-ROM(CD-ROM), digital versatile discs (DVDs), other type optical storagedevices, or a magnetic cassette. Alternatively, the programs may bestored in a memory configured by any combination of some or all of them.Further, a plurality of such memories may be included in an electronicdevice.

In addition, the programs may be stored in an attachable storage devicewhich is accessible through communication networks such as the Internet,Intranet, local area network (LAN), wide area network (WAN), and storagearea network (SAN), or a combination thereof. Such a storage device mayaccess an electronic device, which performs an embodiment of thedisclosure, through an external port. Further, a separate storage deviceon the communication network may access an electronic device whichperforms an embodiment of the disclosure.

In the above-described detailed embodiments of the disclosure, acomponent included in the disclosure is expressed in the singular or theplural form according to a presented detailed embodiment. However, thesingular form or plural form is selected for convenience of descriptionsuitable for the presented situation, and the disclosure is not limitedto a single element or multiple elements thereof. Further, eithermultiple elements expressed in the description may be configured into asingle element or a single element expressed in the description may beconfigured into multiple elements.

While the disclosure has been shown and described with reference tovarious embodiments thereof, it will be understood by those skilled inthe art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the disclosure as definedby the appended claims and their equivalents.

What is claimed is:
 1. A method performed by a user equipment (UE) in a wireless communication system, the method comprising: transmitting, to a first base station (BS), a packet data network (PDN) connection request message; receiving, from the first BS, information on a first network slice selection assistance information (NSSAI), the first NSSAI being selected by a network entity including a packet data network gateway control plane (PGW-C) and a session management function (SMF) from among at least one subscribed NSSAI associated with the UE; transmitting, to a second BS, a registration request message comprising a requested NSSAI including the first NSSAI; and receiving, from the second BS, a registration accept message comprising an allowed NSSAI including a second NSSAI mapped to the first NSSAI.
 2. The method of claim 1, wherein the second NSSAI is for a visited public land mobile network (VPLMN) and the first NSSAI is for a home public land mobile network (HPLMN).
 3. The method of claim 2, wherein the second NSSAI is identified by a network slice selection function (NSSF) entity.
 4. The method of claim 2, wherein, in case of a home routed roaming, the first NSSAI is a HPLMN NSSAI.
 5. The method of claim 1, wherein the first base station supports an evolved packet system (EPS), and the second BS supports a 5th generation system (5GS).
 6. The method of claim 1, wherein the first NSSAI is received via a protocol configuration option (PCO).
 7. The method of claim 1, further comprising: identifying whether the first NSSAI is matched with a user equipment route selection policy (URSP) rule.
 8. A user equipment (UE) in a wireless communication system, the UE comprising: a transceiver; and at least one processor configured to: transmit, to a first base station (BS) via the transceiver, a packet data network (PDN) connection request message, receive, from the first BS via the transceiver, information on a first network slice selection assistance information (NSSAI), the first NSSAI being selected by a network entity including a packet data network gateway control plane (PGW-C) and a session management function (SMF) from among at least one subscribed NSSAI associated with the UE, transmit, to a second BS via the transceiver, a registration request message comprising a requested NSSAI including, the first NSSAI, and receive, from the second BS via the transceiver, a registration accept message comprising an allowed NSSAI including a second NSSAI mapped to the first NSSAI.
 9. The UE of claim 8, wherein the second NSSAI is for a visited public land mobile network (VPLMN) and the first NSSAI is for a home public land mobile network (HPLMN).
 10. The UE of claim 9, wherein the second NSSAI is identified by a network slice selection function (NSSF) entity.
 11. The UE of claim 9, wherein, in case of a home routed roaming, the first NSSAI is a HPLMN NSSAI.
 12. The UE of claim 8, wherein the first base station supports an evolved packet system (EPS), and the second BS supports a 5th generation system (5GS).
 13. The UE of claim 8, wherein the first NSSAI is received via a protocol configuration option (PCO).
 14. The UE of claim 8, wherein the at least one processor is further configured to: identify whether the first NSSAI is matched with a user equipment route selection policy (URSP) rule. 